1. Field of the Invention
The present invention relates to an image processing apparatus which stores an image of an original and outputs an entire area or partial area of the stored image of the original as a color image or a monochrome image.
2. Description of the Related Art
With the development of line sensor scanning devices using a CCD unit and writing devices using laser, there have been released digital copying machines which process digitalized image data. Aside from the copy function, digital copying machines implement a lot of functions such as a scanner function, printer function, and facsimile function, and are now called digital MFPs. MFPs have easy network access, and can transmit the image data stored in a hard disk drive (HDD) or the like inside the apparatus to external devices over a network. MFPs can also receive and store image data from external devices through the network.
MFPs have a variety of uses in offices, and MFPs themselves have been diversified from small to large sizes accordingly. Examples include a small-sized MFP to be paired and installed with a PC so that the operator can easily use the functions of the copying machine, facsimile, printer, and scanner. A medium-sized MFP can be shared among a plurality of members in a department or section, with some productivity and functions such as sorting, punching, and stapling. A department that undertakes a company's copy-related activities in a centralized way, or a company that runs copy-related business itself, uses large-sized MFPs with high productivity, high quality, and high functionalities.
Such a variety of MFPs from small to large sizes have functions common to all classes and functions unique to the respective classes. For example, there is a high need for large-sized MFPs to have functions for postprocessing on plotted paper, such as punching, stapling, and folding, as well as functions for electronic filing concurrent with copying operations. In contrast, what is demanded of small-sized MFPs is the Internet FAX and PC-FAX capabilities, and functions such as high quality image printing on dedicated paper for personal use.
In such a diversified MFP market, it has heretofore been the case that systems having a set of functions needed for respective classes are constructed, sold, and provided. The importance of information values in business has already been recognized, and what is demanded of information communication is not just speed, accuracy, and reliability, but higher understandability and effectiveness as well. With communication technologies getting faster and more prevalent, memories larger in capacity, lower in cost, and smaller in size, and PCs higher in sophistication, there have been provided new functions for effective handling of information using digital data. The provision and implementation of the new functions has also been desired of MFPs which handle digital image data, a part of digital data.
As mentioned previously, MFP's “output” includes an output to paper like copying, and transmission of electronic data as with a scanner and FAX transmission. For electronic data transmission, the form of output varies depending on the intended use. For example, FAX uses a monochrome binary image data format. Scanners use RGB color image data or the like.
While the MFP can output image data through various output means, the individual output means have respective different output characteristics. For paper output, writing units have various characteristics. For scanner distribution, display units vary in characteristic and the like.
Now, one of the functions of the MFP is to identify whether the scanned document is in color or monochrome, make a monochrome output if the original is monochrome, and make a color output if the original is in color.
For example, whether the original is in color or monochrome is determined on the basis of image data that is obtained by pre-scanning the original. Subsequently, processing based on the result of determination whether the original is in color or monochrome is applied to image data that is obtained by fully scanning the original. Since the method includes scanning the original twice, the document scanning speed becomes substantially ½ or less, which has caused an adverse effect on the number of copies output per minute. In addition, there has been the inconvenience that if the original consists of a plurality of pages, a discrepancy can occur between the results of determination whether the original pages are in color or monochrome and the number of scanned pages when the document feeding unit comes to a halt due to paper jamming and the like.
Color image data and monochrome image data may be generated without a pre-scan, in parallel with scanning the original once (see, for example, Japanese Patent Application Laid-open No. 2002-369012). To make a copy, a CMYK image is generated for output printing use. If the result of determination is monochrome, only the K signal is used to make a paper output, in which case the output image quality is lower than that of an image that is generated exclusively for monochrome output. If the CMYK image is generated in consideration of such K signal-based monochrome image output, then the image output as a color document has image quality lower than that of an image that is generated exclusively for color output. According to such a method, when transmitting the image data to a PC or the like, the color image is rendered into an RGB image and the monochrome image into a K image. There is thus a need to generate a color image and a monochrome image simultaneously if the color and monochrome output formats have nothing in common.
Recent MFPs are multi-input multi-output. Examples of the inputs include a scanner image, an image transferred over a network, and a digital camera image read from a PC card or the like. Examples of the outputs include paper printing, FAX transmission, and transmission of image data to a PC.
To make the foregoing multi-output of a single scanned image, some MFPs are configured to store the scanned image inside and make a determination whether the document is in color or monochrome at the time of scanning (as for a similar apparatus, see Japanese Patent Application Laid-open No. 2007-088783). When outputting the stored image, the MFP applies processing corresponding to the result of color/monochrome document determination made at the time of document scanning to the image. Using the result of color/monochrome document determination obtained at the time of image scanning, however, it is not possible to expect an appropriate image output when the intended use of the image at the time of image storing differs from that of reuse time. An example is when an output area of the image different from assumed at the time of image storing is employed for the output.
Japanese Patent Application Laid-open No. 2001-119589 discloses an image processing apparatus which inputs image data of an original by a single document scan, and simultaneously makes a determination whether the original is in color or monochrome (auto color select: ACS) on the basis of the image data. The apparatus retains the result of determination and the image data, and outputs the retained image data on the basis of the result of color/monochrome determination on the original retained. It is mentioned in the same patent document that the ACS area can be set independent of the size, position, and other factors of the original. It should be noted that the result of color/monochrome determination on the original, retained with the image is concerned only with the ACS area that is set at the scanning time. If the output image size is changed from the scanned image size, there is no guarantee that the result of determination stored can be simply used to produce an appropriate image output since the result of determination is not derived from an ACS area that is suited to the changed image size.
Japanese Patent No. 3015045 discloses a color copying apparatus in conjunction with an example of “continuous page copy” where two facing pages of a book are copied in page order. The color copying apparatus makes a color/monochrome determination on each of a plurality of areas to be copied, stores the results of determination, performs color copy processing on images in each area to be copied if the corresponding result of determination is “color,” and performs monochrome copy processing if the corresponding result of determination is “monochrome.” It is also mentioned in the same patent document that the apparatus is similarly applicable to a “continuous enlarged copy” where a single sheet of original is divided into a plurality of areas, and each of the areas is enlarged and copied so that the copy outputs are put together to produce a super enlargement copy. As a concrete method for color/monochrome determination, Japanese Patent No. 3015045 discloses the following example. The color copying apparatus performs the operation of scanning the original for each of the areas to be copied while making a chromatic/achromatic determination on the image signal pixel by pixel to count pixels that are determined to be chromatic. Having performed the operation on all the areas to be copied, the apparatus then performs the operation of determining whether each area to be copied is “color” or “monochrome”: that is, “color” if the proportion of the number of pixels determined to be chromatic in that area with respect to the total number of pixels, or the number of pixels determined to be chromatic itself, exceeds a predetermined value, and “monochrome” if not. With a large number of areas to be copied, however, such a method is inefficient since the operation of scanning the original for each of the areas to be copied is repeated many times. In particular, when a plurality of areas to be copied overlap each other, the overlapping portions of the areas to be copied are inefficiently scanned for color/monochrome determination repeatedly. Moreover, there is a need that counters for counting the numbers of chromatic pixels in respective areas and retaining the count values until the final determination be prepared on a RAM or the like. The greater the number of areas to be copied is, the greater the memory area needs to be prepared on the RAM or the like for the sake of the area-specific counters. This contributes to an increase in circuit scale and cost (with regard to the problem related with the memory capacity, also see Japanese Patent Application Laid-open No. 2007-251835).
In view of the foregoing, a main object of the present invention is to improve the reusability of an image stored in an image processing apparatus such as an MFP which stores the image of an original and outputs an entire area or partial area of the stored image as a color image or a monochrome image. To achieve the main object, it is an object of the present invention to set various areas that overlap each other so that whether the original is in color or monochrome can be determined in each of the areas. Another object of the present invention is to allow highly accurate color determination, to allow area-by-area color determination with a small amount of processing even if the set areas increase in number and intricately overlap each other, and to reduce the memory necessary for color determination. Yet another object of the present invention is to automatically set areas appropriate for color determination on the basis of history information pertaining to user's image output and information on output sheets loaded in the apparatus.